1. Field of the Invention
The present invention relates to a fuel vapor leak detecting apparatus of an internal combustion engine for a vehicle.
2. Background Art
A conventional fuel vapor leak detecting apparatus is configured so that, after an internal combustion engine is stopped, pressurized air is supplied from an air pump to a purge line and a fuel tank, and a leak amount is judged on the basis of the operating current of a motor for driving the air pump (for example, see JP-A-2001-12319 (pages 2 to 6, FIG. 1)).
A conventional fuel vapor leak detecting apparatus has a configuration in which, after an internal combustion engine is stopped, an air pump is driven to supply pressurized air to a purge line and a fuel tank, and a leak amount is judged on the basis of the operating current of a motor for driving the air pump. Therefore, the apparatus requires the air pump, the driving motor, and peripheral pipes, and hence has a complicated structure. Since the internal pressure of the purge line and the fuel tank is indirectly measured on the basis of the operating current of the motor for driving the air pump, the judgment accuracy is limited. The air pump must be operated until the internal pressure reaches a predetermined level. The leak detection is performed after the internal combustion engine is stopped. Therefore, problems in that a battery is consumed, and that the operation of the air pump for detecting leak produces an unpleasant sound are caused.